X-Ray transmissive electrode-shielded wire assembly and manufacture thereof

ABSTRACT

An electrode and a lead wire therefor used with a device for measuring the electrical signals emanating from a living body, such as a cardiograph or electroenecephalograph employed for examination and diagnostic purposes. The electrode consists of two layers of finely divided electrically conductive material, that are printed in laminated fashion on the opposite surfaces of an insulating film. The lead wire comprises plural laminated layers of finely divided electrically conductive material on the opposite sides of an insulating film, the laminated layers being interspersed with or encased by carbon layers and insulating layers. Since X-rays penetrate the electrode and the lead wire, an X-ray photograph may be taken during visual inspection of the biosignals without the image of the electrode and the lead wire appearing on the film to hinder diagnosis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an electrode and a lead wire therefor used fortaking a cardiogram or an electroencephalogram, and more particularly toan X-ray transmissive electrode and a lead wire therefor suitably usedfor taking an X-ray photograph while the electrode remains attached tothe body of a patient, and to a method of manufacturing the same.

2. Description of the Prior Art

Heretofore, metallic electrodes and shielded wire were used for theextraction of biosignals for preparation of a cardiogram or the like.The metallic electrode was brought into contact with the patient's bodyas by use of an adhesive, and one end of the electrode was connected tothe electrically conductive core of the shielded wire, with the shieldportion provided around the metallic electrode being connected to theshield portion of the shielded wire to prevent electrostatic orelectromagnetic noise from mixing with the biosignals.

Furthermore, when taking an X-ray photograph during measurement, theelectrode had to be removed from the patient's body to prevent the imageof the electrode from appearing on the photographic film. Such adverseeffects may be reduced by having the size of the electrode and thediameter of the shielded wire extending from the electrode as small aspossible. However, certain areas desired to be photographed were stillmasked by the electrode and the shielded wire, thus interfering withaccurate X-ray photography and proving a hindrance to diagnosis.

It may be desired from time to time to take an X-ray photograph whilevisually inspecting the waveshape of the cardiogram ofelectroencephalogram. In this case, since the electrode and the shieldedwire cannot be removed from the patient's body, indistinct portions mayappear on the photograph due to obstructions presented by the electrodeand the shielded wire. In order to overcome such problems, electrodespenetrable by X-rays have been devised. For instance, the JapanesePatent Application Laid-Open No. 118873/1977 discloses such an X-raytransmissive electrode comprizing an extremely thin gold layer depositedon a Mylar (polyethylene telephthalate) plastic base film. The electrodeis connected to a single core copper wire clamped and reinforced by aplastic tape. Japanese Patent Application Laid-Open No. 118989/1977 and93681/1978 both disclose substantially carbon electrodes for biologicaluse. It is contemplated that X-ray transmissive electrodes forbiological use may be obtained by using carbon fibers or very thincarbon layers. However, there has not yet been devised an X-raytransmissive electrode and a shielded wire that may be produced easilyand at minimal cost.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide anelectrode and shielded wire of a sturdy construction wherein theshielded wire and the electrode may be integrally made as one unit orassembly from the same material.

Another object of the present invention is to provide an electrode and ashielded wire therefor that are very thin, resilient and compact insize.

A further object of the present invention is to provide an X-raytransmissive electrode and shielded wire therefor which may be producedby a printing technique and which thus lend themselves to massproduction.

A still further object of the present invention is to provide a shieldedwire that may be connected easily to the connectors of measuringequipment, one surface of the wire being used as a signal line and theother surface thereof as a grounding line.

This invention comprises an electrode and a shield wire both formedintegrally on an insulating sheet or film. The sheet or film isdisc-shaped at the portion which contacts the patient's body, andstrip-shaped at the shielded wire portion. On one surface of thedisc-like portion of the insulating sheet, there is provided anelectrode consisting essentially of a layer of finely dividedelectrically conductive material. On the other surface of the disc-likeportion is a shield layer having a larger area than that of saidelectrode.

On one surface of the strip portion of the insulating sheet which iscontinuous to and integral with the disc-like portion, there is aband-like layer of finely divided electrically conducting material,which is also continuous and integral with the layer of the finelydivided electrode material. The band-like layer of the finely dividedconductive material is used as a signal line. Above this signal line isformed an insulating layer. Overlying the insulating layer and thesignal line is a grounding line made of finely divided electricallyconductive material, the grounding line being in turn encircled by acarbon layer to complete the shielding. The electrically conductivematerial and the insulating layer are provided on the strip portion ofthe insulating sheet by printing to facilitate the manufacturingprocess.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the invention willbe more fully apparent from the following detailed description of apreferred embodiment of the invention taken in conjunction with theaccompanying drawings wherein like reference characters refer to likeparts throughout and in which:

FIG. 1 is a plan view of the electrode and shielded wire assembly orunit of the present invention;

FIG. 2 is a cross-sectional view solely of the electrode of the presentinvention;

FIG. 3 is a cross-sectional view solely of the shielded wire of thepresent invention; and

FIGS. 4a to 4e are top plan views, partially broken away, of one endportion of a base layer of a shielded wire showing the successiveprinting of layers of conductive lines and insulating material thereonto form the shielded lead wire 3 of FIG. 1; and

FIGS. 4f to 4h are bottom plan views of the base layer of FIGS. 4a-4e,showing the successive printing of layers of conductive lines andinsulating material thereon shielded wire.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an electrode of the present invention comprises aflat electrode portion 1 in the form e.g. of a disc and a flat shieldportion 2 covering this electrode portion 1. A shielded lead wire 3 isextended from the electrode portion 1 and the shield portion 2.

Referring to FIG. 2, the electrode portion 1 consisting essentially offine particles of electrically conductive material and readilypenetrable by X-rays is applied, as by coating or printing, on to onesurface of a base layer 4 consisting of an insulating film e.g. ofsynthetic material also penetrable by X-rays. The shield portion 2 isapplied by depositing, coating or printing carbon on the oppositesurface of the base layer 4.

The construction of the inventive shielded wire and the method formanufacture of the same will be explained by referring to FIGS. 3 and 4athrough 4h. In FIGS. 4a through 4e, one end portion of a base layer 6for a shielded wire opposite the end connected to the electrode 1 isshown in top plan view, while in FIGS. 4f through 4h, the same endportion is shown in bottom plan view, that is, as seen from thedirection opposite to that of FIGS. 4a through 4e. The progressiveapplication of layers of conductive material and insulation is shownsuccessively in these views.

A signal line 9 is first applied to a base layer 6 integrally connectedto the base layer 4. An electrically conductive paste is used as thematerial for signal line 9, the line 9 being printed on the base layer(see FIG. 4a). Then, a layer of an insulating material 10 is printedover the signal line 9 (FIG. 4b). A further layer of electricallyconductive paste is printed over the insulating material 10 forproviding a grounding line 11 (FIG. 4c). Some of the paste of thegrounding line 11 intrudes into small holes 12 in the base layer 6, oneof such holes being shown in FIGS. 4a through 4c. The conductingmaterial of the grounding line 11 is thus conveyed through these holes12 to the reverse surface of the base 6 for providing so-calledthrough-holes. A carbon layer 13 is printed on the grounding line 11 forshielding (FIG. 4d). An insulating layer 14 is further printed on thecarbon layer 13 (FIG. 4e). On the reverse face of the base 6, anelectrically conductive paste is printed as a grounding line 15 (FIG.4f). Since the conductive paste is applied in this way to the oppositeends of the small holes 12, the grounding lines 11, 15 are connectedtogether via the holes 12. A carbon layer 16 is printed over thegrounding line 15 (FIG. 4g) and an insulating layer 17 is furtherprinted on the carbon layer 16 (FIG. 4h) to complete the shielded wire.As apparent from FIG. 4, since the signal line 9 is provided on onesurface of the base layer 6 and the grounding line 15 is provided on theother face of the base layer 6, the shielded wire may be connected tothe input terminals of measuring equipment with the aid of suitableconnectors.

The shielding operation of the inventive shielded wire will be explainedwith reference to FIG. 3.

The shielding of the signal line 9 is effected by the two groundinglines 11, 15 and carbon layers 13, 16 positioned to encircle the signalline 9. Thus, on the outside of the grounding lines 11, 15, there areprovided the carbon layers 13, 16 over a width to completely overlie thesignal line 9, these carbon layers 13, 16 being in electrical contactwith the grounding lines 11, 15 to prevent the intrusion of externalnoise into the signal line 9.

The operation of the inventive X-ray transmissive electrode will now beexplained with reference to FIGS. 1 through 3.

The electrode portion 1 is placed in contact with a portion of thepatient's body. An electrically conductive adhesive material mayoptionally be coated onto the surface of the electrode portion 1 formaintaining optimum contact between the portion 1 and the patient'sbody. The signal current from the patient's body, obtained through theelectrode portion, is transmitted by the signal line 9 of the lead wire3. The shield carbon portion 2 is connected to the grounding lines 11,15 of the lead wire 3. Since the signal line 9 is surrounded viainsulating layer 10 by the grounding lines 11, 15 and the electricallyconductive carbon layers 13, 16 surrounding these grounding lines 11,15, the signal current emanating from the patient's body is transmittedalong the signal line 9 without mixing with external electrostatic orelectromagnetic noise. The grounding lines 11, 15 may be connectedelectrically with the carbon layers 13, 16 with the aid of small holes12 at the end or at intermediate portions of the lead wire 3 as shown inFIGS. 4a, 4b and 4f.

It is to be noted that any external noise may be passed to groundthrough the grounding lines 11, 15 and thus without interfering withsignal transmission through the signal line. The electrode portion 1 isconnected integrally to the signal line 9, the base layer 4 of theelectrode is connected integrally with the base layer 6 of the lead wire3 and the shield portion 2 is connected integrally to the earthingconductors 11, 15 of the lead wire 3. The carbon as well as syntheticmaterials and electrically conducting materials that constitute theelectrode-shielded wire assembly of the present invention are penetrableby X-rays so that photography can be performed during visual inspectionwithout the necessity of dismounting the electrode portion.

As described above, according to the present invention, the signal line9 and the electrode portion 1 are formed continuously on one surface ofthe insulating base layers 4, 6. The signal line 9 is shielded by thecarbon layers 13, 16 having larger widths than the width of the signalline 9. The grounding lines 11, 15 are located on opposite sides of thebase layer 6 in such positions that that the carbon layers 13, 16 maycontact the grounding lines 11, 15. The X-ray transmissiveelectrode-shielded wire assembly has excellent resilency and anexcellent shielding effect and may be mass produced at reduced cost.

What is claimed is:
 1. A shielded wire used in conjunction with anelectrode for application to a living body, said shielded wire beingadapted to transmit electrical signals issuing from the living body,said shielded wire comprising an elongated strip of an insulating film,a narrow signal line formed on the surface of one side of said strip, afirst layer of electrically conductive material having a width largerthan the width of said signal line and arranged on said one side of saidstrip overlying said signal line, a layer of insulating material locatedbetween said signal line and said first layer of electrically conductivematerial, a second layer of electrically conductive material having awidth larger than the width of said signal line and arranged on theopposite side of said strip underlying said signal line, and groundinglines electrically connected to and arranged longitudinally of saidlayers of electrically conductive material, said signal line beingsubstantially shielded by said layers of electrically conductivematerial and said grounding lines.
 2. A shielded wire according to claim1 in which said signal line comprises a layer of electrically conductivepaste printed on the surface of said one side of said strip.
 3. Ashielded wire according to claim 2 in which said layers of electricallyconductive material comprise layers of fine particles of carbon.
 4. Ashielded wire according to claim 3 in which one of said grounding linescomprises a layer of electrically conductive paste printed on thesurface of said first layer of electrically conductive material remotefrom said signal line and in electrical contact with said first layer ofelectrically conductive material, and the other of said grounding linescomprises a layer of electrically conductive paste printed on thesurface of said opposite side of said strip in electrical contact withsaid second layer of electrically conductive material.
 5. A shieldedwire according to claim 1 in which said signal line, grounding lines andlayers of electrically conductive material are made of materials capableof being penetrated by X-rays.